There is known a technique in which a burner device is provided upstream of an exhaust treatment device in an exhaust gas passage of an internal combustion engine, and a heated gas produced by the burner device is used to increase an exhaust gas temperature, thereby activating the exhaust treatment device (catalyst or the like) to be in a state capable of being treated (for example, refer to Patent Literature 1).
The burner device described in Patent Literature 1 includes a small-sized oxidation catalyst (hereinafter referred to as “burner catalyst”) placed upstream of the exhaust treatment device, having a cross-sectional area smaller than that of the exhaust gas passage of the engine and allowing a portion of the exhaust gas to flow in the burner catalyst, fuel supply means that supplies fuel to the burner catalyst in the exhaust gas passage, and ignition means that ignites and burns the supplied fuel.